Weird Noise '15 991 Turbo S
 

Hey Guys,

Have never posted here but thought I would post this before I went to Porsche.

I am hearing a subtle noise coming from my car. It sounds almost like a beeping noise that progresses as I am driving. When I shut down the car it ends instantly.

It is coming from the rear, but is most apparent if I go near the passenger side rear wheel.

Attaching a video, hopefully someone knows what it is.

Mark

Attachment 1000742

Mine made the very same beeping when new. At the time I was a little PO'd, but.... it goes away.

https://rennlist.com/forums/991-turb...e-beeping.html

:cheers:

Mine made the exact same noise when new. It's some sort of oil relief valve. It went away after a few days.

Mine did it too, and it was *loud* - so I told them I wasn't taking it until they fixed it. I believe they replaced the AOS, and the noise went away.

Good move! I wouldn't be waiting for that noise to go away.....clearly something not right somewhere there. Not good. If it is to do with the AOS then for sure you would want that changed particularly in this DFI engine. You can't afford the AOS not to be at 100% operational efficiency.

Pray tell, what is an "AOS"?

Air to oil separator - separates any oil and oil vapors from entering the air intake via the crank and head breather system. You don't want that especially in a DFI as it can accumulate on the back of the valves and cake up in the intake system.

During operation all engines create an oil misting (some more than others) caused mainly from the rotation of the crank and cams. The bearings on these shafts are pressure fed with oil so there is a splashing effect from coming into contact with any oil bleed-off and also certain pooling of lubricating oil in the heads which lubricates the cam buckets against the cam lobes and other non pressure fed moving parts in the area. The crankcase has to be vented to alleviate the compression formed from the continued oscillation of the pistons. So crankcase compression is breathed/vented into the intake... The AOS sits in between the crankcase and the intake system to remove as much oil vapor as possible...
So if the AOS is faulty (sounding a warning beep) then it isn't doing the job it is there for and the oil laden vapors WILL travel into the intake system. You don't want that I can assure you. Waiting for the beep to go away means you are waiting for the tiny beeper to exhaust itself and wear itself out (which it will do) so it then becomes silent permanently. I guess that is one way of making the noise go away lol.

Thanks for the excellent explanation. Why would a new car have a faulty/clogged AOS?

No worries. Without inspecting the component to see how Porsche has designed it to work I can't really say what the actual issue is which is triggering the beep/alarm. It could well be a case where the valve is shut or partially shut/stuck and the crankcase is not being adequately ventilated. This would create pressure on the seals. Flip side is it's opening but is failing to arrest the oil from the vapor. There is obviously a malfunction somewhere within the device otherwise the beeper wouldn't sound.

1/21/16

Noticed the beep for 1st time yesterday at 6200 miles

How long/involved is the fix?

THX

My '14 991TT just started doing this too. It's at the dealer right now.

Keep us posted ..

1/25/17 Called dealer & had no experience or TSB from Porsche, but eventually did find a "memo"
about the air/oil separator (?). Has to order part.

Crazy thing - after multiple separate instances of hearing the "beep" + having lingering exhaust fumes in my garage smelling very rich, yesterday started the car and took it out for 20 mins...no "beeping".

Part due next week & appt to take it in.....I'll update.

boxer-11....what was the outcome on your TT?

The dealer replaced an intake pipe on mine hoping that would fix it but it didn't. Suspicion now falls on the oil separator but they had to order the part. That should arrive today I'm told.

My experience mirrors yours with the noise being somewhat intermittent. For example, when they came to pick up my car from the house here, it started right up and they loaded it into the trailer and the noise didn't make an appearance at all. The service folks were however able to reproduce the fault no problem once they got hands on it fortunately.

I'll report back once I know more.

Part # 9A1-107-040-02

Here's a DIY I found on 997. Pretty much same as 991

https://rennlist.com/forums/997-foru...rator-diy.html

2/2/17 EDIT: Installed above part.....

Lots of plumbing to get to the oil separator. 100 mile test drive home from dealer - fixed